Display screen or a portion thereof with a graphical user interface



FIG. 1 is a front view of a first embodiment of a display screen with a graphical user interface.

FIG. 2 is a front view of a second embodiment of a display screen with a graphical user interface.

FIG. 3 is a front view of a third embodiment of a display screen with a graphical user interface; and,

FIG. 4 is a front view of a fourth embodiment of a display screen with a graphical user interface.

The outermost broken line showing a display screen forms no part of the claimed design. The remaining broken lines, showing portions of the display screen and portions of the graphical user interface, form no part of the claimed design. 

CLAIM The ornamental design for display screen or a portion thereof with a graphical user interface, as shown and described. 